Nitriles are exceedingly versatile compounds that can be used in the synthesis of a wide variety of compounds, including amines, amides, amidines, carboxylic acids, esters, aldehydes, ketones, imines, and heterocyclics. One of the most important commercially important nitrites is acetonitrile which is a common solvent. Other nitrile compounds are used as herbicides or in the synthesis of detergents or antiseptics. Another of the most commercially important nitriles is acrylonitrile, which is used to make acrylamide, acrylic acid, acrylic fibers, copolymer resins and nitrile rubbers.
One method of production of acrylonitrile is by use of the SOHIO/BP process, which entails the direct ammoxidation of propene (a/k/a propylene) by ammonia vapors in air in the presence of a catalyst (see generally, Acrylonitrile, 1979, Process Economics Program Report, Stanford Research International, Menlo Park, Calif.; Weissermel and Arpe, 1978, Industrial Organic Chemistry, Verlag Chemie-Weinheim New York, pp. 266-270). The wastestream from this process contains a complex mixture of nitriles, including dinitriles, amides and acids at high concentrations. More particularly, the wastestream generally contains nitriles such as acetonitrile, acrylonitrile, succinonitrile and fumaronitrile as well as acrylamide. In addition, cyanide(s) at variable and/or high concentrations is/are often present. The wastestream generally contains high and/or variable concentrations of ammonium sulfate. This hazardous waste effluent cannot be released into the environment due to its toxicity and in the United States is usually disposed of by deep well injection into sub-surface formations. Such disposal cannot be considered to be a "treatment" of the wastestream, but rather is analogous to the process of landfilling.
Outside the United States, it has been common practice to "treat" the wastestream from the production of acrylonitrile by diluting the wastestream to a low total nitrile concentration of about 250 ppm or less and treating by conventional aerated biological wastestream systems, i.e., activated sewage sludge, after wet/air oxidation, which removes volatiles and partially oxidizes many of the organic constituents. Such method of "treatment" is not suitable to efficient disposal of a nitrile production facility wastestream for the following reasons: (1) wet/air oxidation causes volatile compounds to be stripped, creating an air emission problem; (2) dilution of the wastestream necessitates large wastewater treatment facilities to handle the flow and long residence time required to obtain adequate "treatment"; and (3) combination of wet/air oxidation with biological treatment by activated sludge results in high treatment costs. There remains a long, deep felt need in the nitrile production industry for an efficient, cost effective, environmentally sound method to dispose of the effluent of nitrile production plants.
It has long been known that certain microorganisms are useful to convert a nitrile compound to its corresponding amide or acid compound biologically. Both the scientific and patent literature contain numerous references describing the use of nitrile converting microorganisms for the production of specialty chemicals, for example, acrylamide and acrylic acid or acrylate from acrylonitrile. See generally, Kobayshi et al., 1992, Trends Biotechnol. 10:402-408. The nitrile converting microorganisms have been shown to have activities including, nitrilase, which converts a nitrile compound to its corresponding acid compound; nitrile hydratase, which converts a nitrile compound to its corresponding amide compound; and amidase, which converts an amide compound to its corresponding acid compound.
To the knowledge of the present inventor, however, in all these specialty chemical productions using nitrile degrading microorganisms, only a single compound has been employed to induce the relevant activity and only a single nitrile compound has been converted to produce a single desired specialty compound.